1. Field of the Invention
The present invention relates to an introducing liquid for an ink jet head used when ink is introduced into an ink jet head in an ink jet recording method, and to an ink jet head using the introducing liquid, and an ink jet recording apparatus using the ink jet head.
2. Description of Related Art
In an ink jet recording method, ink is ejected from an ink jet head to form ink drops, and part or all of these are adhered to a recording medium such as paper, thereby to make recording. The above ink jet recording method calls for ink which can perform stable ejection without causing any clogging in a nozzle part and an ink passage in the ink jet head, and which can make recording of sufficiently high density with a clear color tone.
Meanwhile, the ink jet head can be roughly divided into thermal type and piezo type. In a recording apparatus of continuous injection type, there is, for example, electrostatic type that controls ejected ink drops by electric field. Specifically, in the thermal type, ink is instantly heated by using a heater so as to generate bubbles, and the force produced at this time is used to eject ink drops. In the piezo type, a piezoelectric device is vibrated to apply force to ink, enabling ink drops to be ejected. As a technique of applying force to ink in the piezo type, there are a method of applying force to ink by a piezo that induces vertical vibration, and a method of applying force to ink by a piezo that induces flexural vibration. In these methods, the force exerted on the ink can be improved by stacking piezoelectric devices. For achieving high density and mass production in the abovementioned piezo type, it seems to be suitable to use a piezoelectric device that induces flexural vibration, and not to stack the same.
In order that the performance of ink can be exhibited sufficiently in the ink jet recording method, especially when using an inkjet head of the piezo type, it is necessary to minimize the loss of pressure wave generated by vibration, and efficiently transmit force to the nozzle part. That is, it is important to create the condition of being completely filled with ink, without leaving any bubbles within the ink jet head. If bubbles remain within the ink jet head, ejection force cannot be sufficiently transmitted to the ink. This causes ejection defects such as non-ejection and injection curve, and the performance required for inkjet recording might not be satisfied. Hence, the condition where the ink jet head is filled with the ink can be said to be important element that controls the performance of the ink jet recording.
One heretofore known method of filling an ink jet head with ink without leaving bubbles, it has been proposed to fill an ink jet head with an introducing liquid before introducing the ink into the ink jet head. The introducing liquid is not more than 2 mm in bubble height immediately after bubbling, and 0 mm in bubble height after five minutes according to Ross Miles method (refer to Japanese Unexamined Patent Application Publication No. 2000-94707). The introducing liquid contains water and a water-soluble organic solvent having surface activity and a lower volatility than water.
However, the ink jet head is made up of various members formed by different materials, and a level difference and minute spacing are present in the areas where these members are bonded to each other. Therefore, even if the abovementioned introducing liquid is introduced, bubbles might be left in an ink passage. As a result, it is difficult to completely remove the bubbles at the time of filling the ink jet head with ink.